Generally, if I'm not mistaken, the cervical fluid/position data you log on FF should be checked at the same time every day. You can check that stuff throughout the day to see if it's changed at all, but I don't believe you are meant to change your data on your chart.
For example, I temp at 7:15 then I use the bathroom, check my cervical fluid and position. Those are the stats I log for the day. If my cervical fluid or position changes during that day, I do not change my data. That would make it inconsistent and not an accurate comparison to the next day's data.
If I'm misinformed, I stand ready to learn and be corrected.